1. Field of the Invention
The present invention relates to a soy milk coagulating device which makes it possible to make tofu and yuba from soy milk with ease in common households.
2. Description of the Prior Art
Tofu has long been mass-produced and sold by tofu manufacturers. Those tofu manufacturers use large-sized soy milk coagulating units, and it has been common to heat soy milk in such units mainly with steam, cut the coagulated soy milk into small portions, and put the portions into containers for sale.
Recently, tofu making devices that have coagulating units of relatively smaller volume (2 to 10 liters) to heat and coagulate soy milk utilizing Joule heat through direct electrification have been developed. The tofu making devices are put into industrial use in izakayas (Japanese-style pubs), restaurants, hotels, tofu specialty restaurants etc., enabling them to serve good tofu relatively easily. According to this method, every part of soy milk starts to generate heat basically at the same time due to Joule heat of the soy milk itself. This prevents convection of soy milk unlike steam heating or the like, thereby providing kinugoshi tofu (silken tofu: soft, smooth, and fine-grained) that is homogenous and dense.
However, conventional Joule heat method tofu making devices need expensive parts for temperature control, current control and the like, which makes the tofu making devices too pricey for common households to purchase. Also, the necessary current amount and the 2 to 10-liter batch of the conventional tofu making devices are too large for household use. In addition, the conventional tofu making devices are not easy to handle in homes.
The conventional tofu making devices put a sensor in the center of soy milk to control temperature. This could evoke resistance in users who are conscious of food hygiene, and presents a risk of sensor breakage when the tofu making devices are in operation or during washing.
In the process of coagulating soy milk by Joule heat, the electric resistance drops greatly in a part of the soy milk that has finished coagulation and gelation, namely, a part that has become tofu, thereby causing a selective current flow. The selective current flow results in further delay in coagulation of not-yet-coagulated part of the soy milk. Therefore, a coagulating unit of relatively large lot (2 to 10-liter batch), in particular, requires high level of coagulation control by control of current or the like, thus making the device expensive.
To make tofu, nigari (natural coagulant) is added to soy milk and then the mixture is heated. When soy milk is heated without adding nigari, yuba (a thin, solid surface layer of soy milk) is formed on the surface of the soy milk. If the Joule heat method tofu making devices are reduced in size and the problems described above are solved, making yuba as well as tofu in households with ease becomes possible.